(1) Field of the Invention
The present invention relates to a new method for knitting a flat knitted fabric, a flat knitting machine for implementing the above-mentioned knitting method, and a novel flat knitted fabric capable of being knitted by using the above-mentioned flat knitting machine. Especially, the present invention relates to the knitting method in which the predetermined knitting movement of the knitting needle is caused by operating each actuator connected to each knitting needle in accordance with a predetermined knitting plan, the flat knitting machine for implementing the above-mentioned knitting method, and the novel flat knitted fabric capable of being knitted by using the above-mentioned flat knitting machine.
(2) Description of the Related Art
A known flat knitting fabric hereinbefore is knitted by moving a plurality of knitting needles arranged slidably in a needle bed fixed on a frame of a flat knitting machine into a knitting position, a tuck position or a welt position by a plurality of cams arranged in a carriage moving reciprocally along the needle bed. Accordingly, to change a knitting design, it is necessary to correspondingly adjust an arrangement of the plurality of cams to the design of the knitted fabric to be knitted. In a case when a jacquard mechanism is used to knit a knitted fabric having a complicated pattern, the plurality of knitting needles are operated by the jacquard mechanism and the change of the knitting design is performed by adjustment of the jacquard mechanism.
There are several restrictions in the knitting of the flat knitted fabric performed by the known conventional flat knitting machine having the above-mentioned constitution, and these restrictions will be explained hereinafter. The knitted fabric knitted by the known flat knitting machine has a plurality of knitting loops of equal size in a course direction. An advantage is obtained in that the knitted fabric having a good aesthetic appearance is provided because the size of the loops is uniform. However a hand knitted fabric is highly evaluated by consumers as a high grade knitted product among knitted fabrics, especially among knitted fabrics for outer wear. The biggest advantage of the hand knitted fabric is the irregularity in the size of the knitting loops, making it possible to obtain an individual appearance and feeling. The appearance and the feeling of the hand knitted fabric cannot be obtained by using the known flat knitting machine having the above-mentioned constitution. Therefore, although the demand for the hand-knitted products is large, it is impossible to satisfy this demand due to limitations in production capacity and high costs.
Also, there are the following problems in the mechanism of the flat knitting machine.
(1) The weight of the carriage is heavy, and thus, when the moving direction of the carriage is reversed at a point where the carriage arrives at an end of the reciprocal movement of the carriage, the inertia force applied to the carriage becomes large. Accordingly, when the moving speed of the carriage is increased to obtain a high productivity, the carriage itself and a mechanism for driving the carriage, such as a chain or the like are apt to be damaged. Accordingly, an increase of the speed of the carriage in the known flat knitting machine is restricted.
(2) It is well known to increase the number of thread feeding units to increase the productivity of the flat knitting machine. However, when the number of the thread feeding units is increased, it is necessary to arrange a number of cams corresponding to the number of thread feeding units, therefore, the weight of the carriage is increased. Further, since the length in the sliding direction of the carriage is increased, the distance of the reciprocal movement of the carriage is increased, so that ratio of a time in which both ends of the carriage run on the needle bed and do not contribute to the knitting of the knitted fabric during the reciprocal movement of the carriage, to the total running time of the carriage, is increased. This means that the time wasted during the knitting is increased. Therefore, there is the above-mentioned restriction to the increase of the number of thread feeding units.
(3) Since the sliding movement of the knitting needle is performed by the cams, it is necessary to make complicated adjustments when changing the design, and an adjustment of the number of coarses and/or wales is performed. Further, the carriage having cams includes many parts, so that maintenance of these parts is time-consuming.
(4) When the speed of the flat knitting machine is increased, the impact of a butt of the knitting needle on the cam, abrasion of the knitting needle when the needle slides against the needle bed, abrasion of the butt of the knitting needle by sliding the butt against the cam, and heat caused by the above-mentioned operations are increased. Therefore, there is an upper limit to the knitting speed that can be used, and there is a problem in that the life of the knitting needle and parts of the flat knitting machine are shortened, even when the flat knitting machine is driven at a usual speed.
As described hereinbefore, although the flat knitting machine manufactured on the basis of the known knitting method is widely used, for improving the productivity of the flat knitting machine and obtaining various knitted fabrics, the known flat knitting machine has several problems to be solved.
Several flat knitting machines having an improved mechanism are proposed. For example, a flat knitting machine having a carriage of which cams are replaced with linear motors was disclosed in Japanese Unexamined Patent Publication (Kokai) No. 54-6979. However, the weight of this carriage having the linear motors is heavy and the linear motors for operating the knitting needle are only installed on the each carriage, so that the knitting needles are only operated at a place where the carriage exist. Therefore it is impossible to improve the productivity of the conventional knitting machine.
A flat knitting machine having a plurality of disks for slidably moving a corresponding knitting needle was disclosed in U.S. Pat. No. 4,127,012. However, this flat knitting machine has a disadvantage that the disk must be replaced with another disk when a knitting design of the knitted fabric is changed and it is impossible to knit a novel flat knitted fabric which cannot be knitted by the known conventional knitting machine.